Socialisation is the most important thing you'll do with a dog, even if they're an adult you need to get them used to as many things as possible so they can live a calm life.
Learn dog body language, so many people get into issues because they can't tell their dog is stressed, or in pain, This is my favourite guide, but you can also learn for free online.
If you're causing your dog pain then you're not training their minds and setting you both up for failure. Find a different way to get what you want.
Most issues people have with their dog is because they're not getting the correct physical or mental exercise.
Understand the breed you have as it will teach you how to make your dog comfortable.
Sane people don't try to kill themselves